First of all, a wireless local area network (WLAN) system is described as one example of a system to which the present invention is applicable.
The standard for WLAN (wireless local area network) technology is being developed as IEEE (institute of electrical and electronics engineers) 802.11 standard. IEEE 802.11a/b uses an unlicensed band on 2.4 or 5 GHz. The IEEE 802.11b provides a data rate of 11 Mbps, while the IEEE 802.11a provides a data rate of 54 Mbps. IEEE 802.11g applies OFDM (orthogonal frequency division multiplexing) on 2.4 GHz to provide a data rate of 54 Mbps. IEEE 802.11n applies MIMO-OFDM (multiple input multiple output-OFDM) to provide a data rate of 300 Mbps for 4 spatial streams. The IEEE 802.11n supports channel bandwidths up to 40 MHz. In this case, a data rate of 600 Mbps is provided.
The aforementioned WLAN standard uses a bandwidth up to maximum 160 MHz and supports 8 spatial streams, and there is an ongoing discussion about IEEE 802.11ax standardization through IEEE 802.11ac standard supportive of a speed of maximum 1 Gbit/s.